Heat exchanger



K- J BRADY ETAL HEAT EXCHANGER April 18, 1967 Original Filed Feb. 23, 1965 PATENT AGENT United States Patent This application is a continuation of application Ser. No. 434,549, filed Feb. 23, 1965, now abandoned.

The present invention relates generally to heat exchangers and more particularly to heat exchangers designed primarily for the cooling and condensation of hotvapors.

In the food industry, certain viscous materials such as salad dressing are cooked at elevated temperatures and subsequently must be cooled prior to delivery into bottles for distribution to the consumer. Quite typically, salad dressing received from a cooker at a temperature of approximately 190" F. should be reduced to a temperature of approximately 90 F. before the same is bottled. For this purpose, the material is delivered to a so-called flash chamber which is evacuated to a relatively high degree (e.g., 29 inches of vacuum) which effects the cooling of the material and the same can thereafter be pumped to the bottles or other containers. Exposure of the material to the vacuum eflFects vaporization of water and other volatile constituents in the mixture which in turn must be cooled and condensed for elfective removal. Such cooling and condensation has been achieved by heat exchange mechanism whose effectiveness is limited so that, upon occasion, the capacity of the vacuum pump is exceeded and the requisite cooling is not always achieved. Additionally, return or flash-back" of the vapors to the main evacuation chamber is a frequent occurrence which in turn limits the reduction of temperature of the salad dressing.

Accordingly, it is a principal object of the present invention to provide a heat exchanger which is particularly efiective for vapor condensation in an evacuated system of the type mentioned.

tween the cooling medium and the vapors to maximize the efliciency of the heat exchange.

More specifically, it is a feature of the invention to provide for a controlled spray of a cooling medium entirely across the path along which the hot vapors are constrained to move.

Additionally, as a supplemental heat exchange mechanism, it is a feature of the invention to provide that the aforementioned cooling medium which is brought into direct contact with the hot vapors is also utilized through contact with metallic cooling fins to provide an additional reduction in temperature of the vapors to enhance the over-all efiiciency of the entire heat-exchange mechamsm.

These as well as other objects and features of the invention will become more apparent from a perusal of the following description of an exemplary embodiment of the invention shown in the accompanying drawing wherein the figure is a side elevation, partly in section, illustrating, in somewhat diagrammatic form, an apparatus for cooling salad dressing and effecting condensation of the Patented Apr. 18, 1967 ice hot vapors with a heat exchanger incorporating the features of the invention.

As shown in the figure, an upright, generally cylindrical tank 10 is arranged to receive salad dressing from an inlet pipe 12. More particularly, the inlet pipe 12 is connected at its remote end to a cooker (not shown) for the salad dressing and terminates in a tangential opening at the upper end of the tank. The salad dressing, in the form of a viscous liquid drops by gravity towards the lower end of the tank 10 for delivery through an outlet opening 14 to a suitable pump and then to a conventional filling mechanism (not shown) forming no part of the present invention.

The interior of the tank 10 is evacuated to a relatively high degree (e.g., 29 inches of vacuum) which serves not only to draw the viscous material through the inlet pipe 12 into the tank, but also effects a cooling thereof through the expansion and vaporization of the volatile components of the viscous material. Such an arrangement is well known in the art and is generally referred to as a flash chamber. The vacuum is established by a vacuum pump 16 whose suction line 18 terminates at an intermediate level in a vertical conduit 20 whose upper end is in turn connected by a horizontal conduit 22 to the upper end of the described tank 10. While the viscous material is being withdrawn from the lower end of the tank 10, the vapors formed by water and other volatile constituents of the entire mixture are drawn through the horizontal conduit 22 and thence downwardly toward the suction line 18 of the vacuum pump 16, as indicated by the arrows in the figure.

The general arrangement as thus far described is conventional and, in accordance with the present invention, a heat exchanger 30 is positioned in the vertical conduit 20 to cool and eifect a condensation of the heated vapors delivered to the upper end of the vertical conduit from the tank 10.

More particularly, a tube 32 is centrally supported within the vertical conduit 20 adjacent its upper end and is arranged interiorly to receive water from an inlet line 34 for flow downwardly through the tube. At its lower end, the rim of the tube 32 is formed with an outwardly diverging frusto-conical surface indicated at 36, which together with a movable member 38 whose exterior is also of frusto-conical configuration, forms a nozzle 40 which directs the water in an outwardly and downwardly divergent spray indicated at S towards the side walls of the vertical conduit 20. Accordingly, the vapors moving downwardly through the vertical conduit 20 come into direct contact with the screen of water particles formed by the described spray S'to effect an efficient direct heat exchange mechanism. Generally speaking, the water is delivered to the heat exchanger 30 at a temperature of about 70 so that a considerable temperature difierential exists between it and the heated vapors.

The amount of water vapor sprayed into the conduit 20 is controlled by axial motion of the inner nozzle member 38 which, for this purpose, is mounted on an axial rod 42 extending entirely through the tube 32 and threaded for engagement with interiorly threaded holes in spaced supporting members 44. The upper end of the rod 42 projects above the tube and mounts a handle 46 which may be grasped to turn the rod and accordingly effect a variance in vertical disposition of the rod and the movable nozzle member 38 at its lower extremity.

To supplement the heat exchange achieved through direct contact between the heated vapors and the Water spray S, the tube 32 is preferably provided with a plurality of vertically-spaced, horizontally-disposed fins 48 secured to the exterior of the tube so as to provide an initial contact with the heated vapors and instigate an indirect heat exchange relationship, the water within the tube cooling the fins 48 and the fins, in turn, cooling the heated vapors. Such fins 48 also serve to effect a turbulence of the vapor flow through the annular passageway between the central tube 32 and the surrounding vertical conduit 20 to maximize contact between the vapors and the surfaces of the fiins.

Below the fins 48 and above the divergent spray S of Water at the lower end of the heat exchanger 30, an annular baflie 50 is preferably supported in the interior of the vertical conduit 20 to deflect the partially cooled vapors inwardly and thereafter effect maximal dispersion thereof against the water spray again enhancing the surface contact between the heated vapors and the encountered spray of water. It is to be particularly observed that since the Water spray S preferably diverges downwardly in the direction of vapor flow, the described heat exchange mechanism also functions somewhat in the fashion of a conventional oil-diffusion pump to assist in maintainance of the desired high degree of evacuation of the tank. In fact, the described heat exchanger can be visualized as both a heat exchanger and a vacuum-creating structure.

Below the spray of water, a plurality of staggered baffles 52 are supported in the vertical conduit 20 to provide a tortuous path for flow of both water and vapor downwardly through the central portion of the vertical conduit, thus achieving yet further contact between the two flowing materials and a consequent further reduction in the vapor temperature and ultimately substantially complete condensation thereof for subsequent admixture with the water and delivery through the lowermost end of the vertical conduit 20 to a water exhaust pipe 54 which can be connected to a suitable outlet water pump (not shown).

The lowermost of the described baffles 52 is of inverted, cup-shaped configuration to essentially cover the entrance end of the vacuum pump suction line 18 to thus preclude entry of water or condensate thereinto. Thus, only vapors remaining in the vertical conduit 20 can move around the lower rim of such inverted cup and be drawn into the suction line 18 and thence into the vacuum pump 16. This vapor flow is indicated by the curved arrows as opposed to the continued downward movement of the Watercondensate mixture also indicated by the arrows in FIG. 1.

The overall action of the described arrangement is extremely eflicient. The salad dressing delivered to the tank is at a temperature of 190 F., as previously mentioned, and is withdrawn from the lower end thereof at a temperature of approximately 90 F. which is sufiiciently low to enable the filling operation to proceed. In turn, the heated vapors are condensed to a considerable extent by passage through the described heat exchange mechanism so that substantially all of these condensed vapors are withdrawn with the water at the lower end of the vertical conduit 20. Whereas the inlet water temperature, as mentioned, is 70, the water delivered through the outlet at the lower end of the vertical conduit is approximately 85 F. in practice to support the contention that the described mechanism is highly efiicient in its heat exchange function.

The spray of water and, as a result, the velocity and total volume of water flowing can be adjusted by control of the water source and axial motion of the movable nozzle member 38 to optimize the heat exchange relationship, such velocity and amount varying with the rate of salad dressing delivered to the tank and also the capacity of the vacuum pump 16. The settings of the nozzle and water supply can readily be optimized by simple observation of the output temperatures of both the water and the salad dressing.

Various detailed modifications in the described structure can be made without departing from the spirit of the invention and the foregoing description is therefore to be considered purely as exemplary and not in a limiting sense. The actual scope of the invention is to be indicated only by reference to the appended claims.

What is claimed is:

1. A heat exchanger for cooling hot vapors flowing through a conduit towards a vacuum pump which comprises a tube centrally supported in the conduit wherefore the vapors are constrained to flow through an annular passage externally of said tube and internally of the conduit,

means for supplying a fluid coolant to the interior of said tube, and v a nozzle at the end of said tube arranged to direct a spray of said coolant outwardly toward the walls of the conduit.

2. A heat exchanger according to claim 1 which comprises a plurality of annular fins projecting outwardly from said tube.

3. A heat exchanger according to claim 1 wherein said nozzle is arranged to direct the spray of the coolant in a path diverging in the direction of vapor flow.

4. A heat exchanger according to claim 1 wherein said nozzle is adjustable for the control of the amount and velocity of coolant sprayed therefrom.

5. A heat exchanger according to claim 1 which comprises a plurality of bafiies beyond said tube in the direction of vapor flow through the conduit.

6. Apparatus for cooling hot salad dressing or similar viscous materials having volatile constituents which comprises a tank having an inlet adjacent its upper end and an outlet adjacent its lower end,

3. vacuum pump,

means including a vertically-disposed conduit connecting said vacuum pump to the top of said tank whereby the tank is evacuated and volatile vapors are withdrawn from said tank to flow downwardly through said vertical conduit,

a tube centrally supported in said conduit wherefore the vapors are constrained to flow through an annular passage externally of said tube and internally of said conduit,

means for supplying a liquid coolant to the interior of said tube, and

a nozzle at the end of said tube arranged to direct a spray of the coolant outwardly toward the walls of the conduit.

7. A cooling apparatus according to claim 6 wherein said vacuum pump has an inlet suction line terminating centrally within said vertical conduit at an intermediate level therein, and which comprises an inverted cupshaped baflie positioned over the end of said suction line to deflect liquids away from said suction line and permit the same to fall by gravity toward the bottom of said vertical conduit.

8. A cooling apparatus according to claim 7 which comprises a liquid pump connected to the lower end of said vertical conduit.

9. Apparatus for cooling hot salad dressing or similar viscous materials having volatile constituents which comprises a tank having a salad dressing inlet adjacent its upper end and an outlet therefor adjacent its lower end,

a vacuum pump,

means including a conduit connecting said vacuum pump to said tank whereby the tank is evacuated and volatile vapors are Withdrawn from said tank to flow through said conduit,

a tube supported in cooperative position with respect to said conduit wherefore the vapors are constrained to contact an external surface of said tube,

means for Supplying a liquid coolant to the interior of said tube, and

a nozzle arranged to direct a spray of coolant into the conduit.

10. A cooling apparatus as recited in claim 9 in which baffle means is provided for protecting said vacuum pump from direct entry of liquids.

11. Apparatus for cooling hot salad dressing or similar viscous materials having volatile constituents which comprises a tank having a salad dressing inlet adjacent its upper end and an outlet therefor adjacent its lower end,

21 vacuum pump,

means including a conduit connecting said vacuum pump to said tank whereby the tank is evacuated and volatile vapors are withdrawn from said tank to flow through said conduit,

tube means operatively related to said conduit to bring the vapors in the conduit into contact with said tube means,

means for supplying a liquid coolant to the interior of said tube means, and

nozzle means for discharging a spray of coolant inside of said conduit and across the path of said vapors therein.

12. The process of preparing a salad dressing which comprises WILLIAM J. WYE, Primary Examiner.

cooling the dressing at an elevated temperature,

subjecting the dressing while at the elevated temperature to a vacuum,

separating the salad dressing and the vapors removed therefrom by the vacuum,

conveying the vapors through an elongated path, and

subjecting the separated vapors to the cooling and condensing action of a coolant along a substantial portion of said path.

13. In the method as recited in claim 12 which includes providing a liquid spray in said path through which the vapors must pass.

14. In a method as recited in claim 13 in which the liquid spray is directed to provide a component of movement thereof in the direction of discharge of the vapors.

15. In a method as recited in claim 13 which comprises carrying the vapors and the liquid from the spray simultaneously through a tortuous discharge path.

References Cited by the Examiner UNITED STATES PATENTS 8/1941 Smith 34-92 4/1961 Berkeley 62100 

12. THE PROCESS OF PREPARING A SALAD DRESSING WHICH COMPRISES COOLING THE DRESSING AT AN ELEVATED TEMPERATURE, SUBJECTING THE DRESSING WHILE AT THE ELEVATED TEMPERATURE TO A VACUUM, SEPARATING THE SALAD DRESSING AND THE VAPORS REMOVED THEREFROM BY THE VACUUM, 